In a conventional X-ray monochromator, a crystal is elastically and slightly bent; then, a polishing finish is performed in order to uniformly obtain a predetermined diffraction through polishing. Alternatively, in a reversed order, the crystal is polished first and then subjected to bending deformation. A Johann-type or Johansson-type monochromator crystal, which is deformed within an elastic limit, has been in practical use.
However, with such conventional manufacturing methods of X-ray monochromator crystals, which are deformed within the elastic limit, a bend having a high curvature could not be applied. Accordingly, the conventional manufacturing methods could only be used for large-sized X-ray devices. Further, in cases where a considerable decrease in angle resolution and in integrated reflecting power is permitted, plastically deformed crystals having a low yield stress are in some cases used.
An X-ray Johann-type or Johansson-type monochromator is usually manufactured using either a method in which, subsequent to a cutting/polishing process, the crystal is additionally subjected to an appropriate elastic deformation and kept deformed, or a method in which a crystal that can be easily processed is plastically deformed.
In such methods, for example, a crystal that can be easily processed, such as a LiF crystal, is cut after having been subjected to slow elastic deformation; alternatively, such a crystal is elastically deformed by forcible attachment to a mold. Further, as disclosed in Patent Literature 1, inventors of the present application achieve an invention relating to a technology to manufacture a curvature distribution crystal lens. This technology uses as a basis a Si (100) single crystal having mostly a covalent bond, and the curvature distribution crystal lens is obtained through press molding for plastic deformation at a high temperature and under a high pressure.
However, the technique using elastic deformation has problems with regard to stability of a deformed amount in retention of the elastically deformed crystal and with regard to aging; further, because the deformation is kept within an elastic limit, an anticipated angle is limited to an extremely small value. Further, in the case of a technique using plastic deformation, as the crystallinity deteriorates due to the plastic deformation, a half-value width significantly increases and in addition, the integrated reflecting power decreases.
Further, it has become apparent that, even though it is possible to obtain a uniformly curved single crystal as a result of the plastic deformation using as a basis a Si (100) surface (as described in Patent Literature 1), an area uniformly deformed as described above becomes rather small and an incident angle range of an X-ray crystal spectrum becomes small. As a result, there is a demand for a curvature distribution crystal lens having a wide incident angle range and a high light focusing accuracy.
Citation List
Patent Literature 1
International Publication No. WO 2007/072906 (Publication Date: Jun. 28, 2007)